Higgs b ranching ratios study

Higgs branching ratios study

Oct. 13 2012Hiroaki Ono (NDU)

Oct. 13 2012 ILC Physics WG general meeting

Current status of Higgs BR study

• Higgs branching ratios analysis publication– Ecm=250 and 350 GeV Hbb, cc, gg channel– Submitted to EPJ, now under review…

• Detailed Baseline Document (DBD) study– Detector benchmarking study for ILD• e+e-ννh @ 1 TeV branching ratio study

– Physics chapter• Update results with Higgs mass of 125 GeV


vvh detector benchmarking study


e+e-vvh is one of the DBD detector benchmarking processObservable: cross section times branching ratios (σ×BRs)Decay channels: hbb, cc, gg, WW*, μμ

• Jet energy resolution (Reconstructed Higgs mass)• Jet clustering and reconstruction (with γγ BG overlay)• Flavor tagging performance (b/c tagging)• Tracking performance, momentum resolution (Hμμ)

Evaluate ILD detector performance at Ecm=1 TeV

We perform the full detector simulation with latest reconstruction packages in ILD

Higgs physics at ILC 1 TeV


Higgs mainly produced via e+e- νeνeh (WW-fusion)

Final state only comes from Higgs decay• Hbb, cc, gg (two jets)• HWW* (four jets via fully hadronic decay)• Hμμ (dilepton)γγhadron BG is also overlaid as same as CLIC study

Simulation condition


Higgs mass: Mh=125 GeVCM energy: Ecm=1 TeV Beam polarization: P(+-0.8, -+0.2)L=500 fb-1 for both pol.

Channel BRsbb 57.8%cc 2.7%gg 8.6%WW 21.6%μμ 0.02%

Detector model: ILD_o1_v05Simulation: Mokka v01-14-01-p00Reconstruction: Marlin v01-16-00• Detector mass simulation was finished• Mass reconstruction is still on-going

Higgs signal sample

Softwares

Higgs BRs @Mh=125 GeV

Hbb, cc, gg channel


Hbb, cc, gg hadronic

• Simply final state forms two jets• γγhadron background is also overlaid on signal

• Apply forced two jet clustering at firstTry different jet clustering algorithm• Durham (LOI)• kt algorithm (used in CLIC CDR for hadron collider)• R parameter(jet-radius) should be tuned

Only check signal samples at this moment…

Invariant mass distribution


Without γγhadron overlay

Invariant mass (GeV) Invariant mass (GeV)

w/o BG overlay w/ BG overlay

• Cut on the angler distribution• Different jet clustering

DurhamkT jet algorithm (as same as CLIC CDR)

kT jet clustering


Invariant mass (GeV)

Dijet reconstruction with γγhadron BGUse Durham w/o BG overlay

Optimize R parameter forkT algorithm

R=1.0~1.3 looks suitable

Check with forward particlebefore jet reconstruction

Jet reconstruction with PFO cut


Dijet reconstruction with γγhadron BG

w/o BG w/ BG kT w/ BG kT (cosθ<0.98) W/ BG inv. M (cosθ<0.98)

Check with small statisticsSlightly improve the PFO cosθ cut

Set R=1.1 for kT algorithm

HWW* channel


HWW* (one on-shell W) from Higgs decayHWW*qqqq fully hadronic decay channel is considered

h

W1

W21. Apply forced four jet clusteringEmploy kT algorithm with R=1.0

2. Jet paring for W1, W2 (W1 is on-shell with J1, J2)Select best candidate with minimizing χ2

Reconstructed masses


MH Mw1 Mw

Conclusion

• We concentrate the studies for DBD– vvH @ 1TeV– Detector simulation has been finalized– Reconstruction is now still on-going

– Schedule is quite tight but need to finalize by LCWS12


Higgs b ranching ratios study

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